We purchased our Blue Ox Aladdin tow bar used on eBay a few years ago and saved a lot of $$$. It was a very good shape and at the first rally we went to, Blue Ox service techs were there and they went over it, checked everything, no charge. They also check it every year for no charge when we go to the Back Home Rally. If there is any wear at all on any part, they always replace it, again no charge.
As far as the mounting plate, we purchased it new from Blue Ox website.
With Blue Ox's great service, I would purchase any brand, as long as it was Blue Ox.